Fred used to be rather timid with the Amano Shrimps (japanese algae eating shrimp) and he would check them out, then by-pass them. His favourite spot is to swim through the space between the heater and the glass. But since the shrimps were grazing there, he swam around his normal route.

So he started making bubble nest and all of a sudden he got aggressive. He would lounge out of the water at my index finger instead of following it under the water. Then...the unbearable happened, I think I found the remains of one of the shrimp while cleaning today. I hope it is rotten plant roots but it looks kind of like bits of the body...

SO is this hormonal ? Is he claiming his territory with the nest and start taking on the shrimps? The shrimps are about 1 1/4" long. I had the two shrimps in the tank since 1/16/13. I have plants to allow them to hide. But those shrimps like hanging at the filter outflow sponge which may explain their high profile visibility since Fred likes to surf the currents there every now and then.